The present invention generally relates to methods and apparatus for repairing meniscal defects, and in particular to tissue repair scaffold devices having enhanced properties.
The meniscus is specialized tissue found between the bones of a joint. For example, in the knee the meniscus is a C-shaped piece of fibrocartilage which is located at the peripheral aspect of the joint between the tibia and femur. This tissue performs important functions in joint health including adding joint stability, providing shock absorption, and delivering lubrication and nutrition to the joint. As a result, meniscal injuries can lead to debilitating conditions such as degenerative arthritis.
Meniscal injuries, and in particular tears, are a relatively common injury. Such injuries can result from a sudden twisting-type injury such as a fall, overexertion during a work-related activity, during the course of an athletic event, or in any one of many other situations and/or activities. In addition, tears can develop gradually with age. In either case, the tears can occur in either the outer thick part of the meniscus or through the inner thin part. While some tears may involve only a small portion of the meniscus, others affect nearly the entire meniscus.
Unfortunately, a damaged meniscus is unable to undergo the normal healing process that occurs in other parts of the body. The peripheral rim of the meniscus at the menisco-synovial junction is highly vascular (red zone) whereas the inner two-thirds portion of the meniscus is completely avascular (white zone), with a small transition (red-white zone) between the two. Degenerative or traumatic tears to the meniscus which result in partial or complete loss of function frequently occur in the white zone where the tissue has little potential for regeneration. Such tears result in severe joint pain and locking, and in the long term, a loss of meniscal function leading to osteoarthritis.
Although several treatments currently exist for meniscal injuries, the treatment options provide little opportunity for meniscal repair or regeneration. The majority of meniscal injuries are treated by removing the unstable tissue during a partial meniscectomy. Once the tissue is removed no further treatment is conducted. Most patients respond well to this treatment in the short term but often develop degenerative joint disease several years (i.e., after more than about 10 years) post operatively. The amount of tissue removed has been linked to the extent and speed of degeneration. When the majority of the meniscal tissue is involved in the injury, a total meniscectomy is conducted. If the patient experiences pain after a total meniscectomy without significant joint degeneration, a secondary treatment of meniscal allografts is possible. The use of allografts is limited by tissue availability and by narrow indications.
For meniscal tears that can be stabilized in vascularized areas of the meniscus, the tears can be repaired with suture or equivalent meniscal repair devices such as RapidLoc (DePuy Mitek) and FasT Fix (Smith & Nephew). While these repairs are successful in approximately 60-80% of the cases, the percentage of injuries which meet the criteria to be repaired is 15% or less. Repair criteria are based not only on vascularity and type of tear but also stability and integrity of the meniscus, stability of the knee and patient factors such as age and activity. If the repair does fail, the next possible course of treatment is either a partial or total meniscectomy.
Despite existing technology, there continues to exist a need in this art for novel tissue repair devices capable of encouraging meniscal tissue regeneration, as well as methods for using such tissue repair devices.